Such an exchanger can be a heat exchanger, a substance exchanger, or separator. More particular the invention relates to an exchanger to be used at elevated temperature. Because of the conditions of use, ceramic material to provide sufficient service life is used in the art. As example hollow fibre membrane tubes with small tube diameter are mentioned. At higher temperature levels polymer membranes are no longer usable. Advantages of ceramic membranes are high temperature resistivity, mechanical stability and normally those membranes are not sensitive to chemical attack in for example, corrosive surroundings. An example for a method to produce a ceramic hollow fibre membrane allowing for high fluxes is disclosed in EP-0 693 961 A1.
In practical use only tubes are not sufficient. They have to be incorporated in a module to make practical use thereof. Generally, such a module comprises an enclosure and a pipe plate for receiving the ends of the hollow tubes as well as possibly further plates to distribute flows both in the hollow tubes and around those tubes.
Up till now it was technically not feasible to produce in an economical way pipe plates which could withstand relative high temperatures and in which also some mechanical loading is observed and which can be scaled up easily.
It has been shown that many gas separation processes can be conducted at high temperature with ceramic membranes. An example is the `Knudsen` separation with gamma-Al.sub.2 O.sub.3 membranes, separation of hydrogen from a mixture of gases with silica membranes (300-500.degree. C.), isomer separation with zeolite membranes (.+-.500.degree. C. max.) and electrochemical separation of oxygen from air with mixed ionic-electronic conducting materials (800-1000.degree. C.). These are only examples for which high temperature exchangers could be used, more in particular the hollow fibre membrane tubes. In order to scale-up these processes high temperature resistant membrane modules allowing for high fluxes have to become available for relative low prices.
JP-A-61 004509 discloses a heat exchanger comprising a bundle of thin glass membrane tubes. Because at a relatively low temperature glass material will lose its strength and start yielding, the use of a heat exchanger made according to the Japanese patent application is restricted to a relatively loss temperature. Furthermore, additional measures are necessary to complete the heat exchanger. The glass tubes are connected to the pipe plates by introducing them in a mixture of glass and ceramics. Through heating, a sintering and bonding step would occur. Glass will function as a binder. However, if a higher temperature use is desired it is no longer possible to use glass as a binder.